Speaking from the stage at TechCrunch’s Disrupt conference in San Francisco, Facebook CEO Mark Zuckerberg is taking an usually candid approach to answering question about the company’s IPO and its missteps. His first sentence, in fact, stated what we know to be true – “The performance of the stock has obviously been disappointing.”

But Zuckerberg has a lot of explanations for why that is, as well as what’s coming in the future. First and foremost, he talks about Facebook’s expansion into mobile. Zuckerberg believes that, in the next three to five years, the performance of the company is going to “depend on how we do with mobile.” But while many of us aren’t overly enamored with Facebook’s mobile offerings, Zuck believes that there’s a lot more to be said for what’s already available.

“It’s fundamentally misunderstood how good mobile is on Facebook. There’s more engagement, they’re spending more time. We also think that we’re going to make more money on the time that they spend on mobile.”

Zuckerberg chalks up the importance of mobile to the fact that, as Facebook has found, mobile ads have considerably higher engagement rates than the right-column ones on Facebook.com. Taking things a step further, Zuckerberg admits that Facebook’s “biggest strategic mistake” was working with HTML5 instead of native apps.

“On iOS and Android you can just do so much better by doing native work and we needed to do that.”

Zuckerberg talks about some of the rules at Facebook, and how it has changed his role. “We have a rule that if you write the code you have to support your code.” He states that, in order to respect the position of the other engineers within the company, he codes only on the side.

Instagram

Zuckerberg says that he wanted to get to know the people who were doing “great things on our platform”, so that began his relationship with the Instagram team.

“We can help them grow…but we’ll get to these things more slowly that we want to..Maybe we should join. We think Instagram is amazing and we want it to grow to hundreds of millions of users.”